


Birthday

by SpicySans



Category: Undertale (Video Game)
Genre: Don't Read This, Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Goddamn I still can't tag, I'm bad at smut, Never said it was gonna be good though, Reader is 18, SO SORRY, Sans doesn't know reader is trans, Sans is 22, Sans is awkward, So don't expect it to be, Trans Male Character, Um this sucks, Welp I'm sorry, idk what this shit is, reader is trans, sexual content ahead
Language: English
Status: Completed
Published: 2017-10-28
Updated: 2017-10-28
Packaged: 2019-01-25 16:02:14
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,405
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12535636
Author URL: https://archiveofourown.org/users/SpicySans/pseuds/SpicySans
Summary: Reader is turning 18 today, Sans has a big surprise for him.(couldn't think of a title)(Idk what this shit is, its my birthday today so I wanted to write a birthday themed fanfic, but I wanted to make it slightly different with the reader being trans bc I don't see many fics like that)





	Birthday

You woke to the sound of your alarm clock buzzing, groaning, you felt on your side table, trying to find your blasted phone to turn the alarm off. After succeeding in this, you took note of the date. Your birthday. _Great._ Another year older, another year closer to death, another year you gotta spend _alone_. No one to love you.  
Well. You had friends who you were pretty sure loved you, but that isn't what you wanted. You wanted someone who loved you romantically, someone you could cuddle up to when you had nightmares, someone to kiss you and watch stupid rom-coms with. Someone to look past the guy who happened to have a vagina between his legs. Of course that would never happen. What better way to top it off that you were madly in love with Sans, your best friend.

Sighing, you rolled out of bed and shuffled towards the bathroom, looking at yourself in the mirror above the sink. You looked absolutely fucking dead. _Heh accurate_. You picked up your toothbrush and squeezed a bit of the minty toothpaste onto it before beginning you brush your teeth. God-fucking-damn you hated morning breath.  
Once you finished brushing your teeth, you stripped and hopped into the shower, basking in the warm, tracing the surgery scars around what would've been, your breasts. At least Toriel is accepting towards you. She was a great mother and you loved her so much, you'd give her the world if you could. Hell, you'd give all of your friends anything their souls desired if you could.

Shivering slightly as you stepped out of the warm water, you turned the shower off and wrapped a towel around yourself then headed towards your bedroom to get dressed. Your pick for the day was a simple black jumper with some ripped jeans, converse and a beanie, just as you finished you heard a knock at your door.  
'H-hey kiddo, Toriel sent me up to see if you were awake.' _Sans._  
You checked yourself over once more before opening your bedroom door to be greeted by your smiley trashbag of a best friend.  
'Yup, I'm done, Sans' You couldn't help but smile up at him, just seeing him was making your birthday a whole lot better.  
'Lets'a go then,' he grinned taking your wrist and pulling you into a hug 'oh and happy birthday.'  
He pulled away a second later, dragging you downstairs by your wrist, completely ignoring your red-tinted cheeks.

'Heya Tori, she's up'  
'Oh my child! Happy birthday' came your mother cheerful voice before you were pulled into a bone-crushing hug.  
'T-thanks mum' you said as she let go, breathing in as much oxygen as possible as she pulled away from the hug.  
'HUMAN! HAPPY BIRTHDAY!' you were picked up off the ground and twirled as Papyrus hugged the life out of you.  
'Thanks Papy!' you hugged him back the best you could as he continued to throw you about before putting you back down on the floor.

'So... wanna go watch a movie?' Sans asked, already making his way towards the sofa and turning the TV on.  
'Yeah! Saw?' you asked excitedly as you bounced onto the seat next to him. 'Heh, sure kiddo' came his reply as he put the movie on.  
'WELL IF YOU TWO ARE WATCHING THAT SCARY MOVIE I WILL GO HELP TORIEL IN THE KITCHEN, HAVE FUN!' and with that, Papyrus, stormed into the kitchen.  
You and Sans shared a glance before laughing at his little brothers' reaction before cuddling up with a blanket as the movie started.

Although you've seen the movie so many times, you always get slightly grossed out. Each time this happens you unknowingly cuddle closer to Sans, so by the time the movie ended you were practically sitting on his lap. 'S-sorry' you stuttered, realizing the position you had got yourself into during the duration of the film.  
'All cool, kid. Though it seems they still haven't finished in the kitchen? Didn't know it took so long just to bake a cake, heh.' He said, clearly trying to lighten the mood after the gruesome film.  
'Well.. I think mother said something about creating a layered cake...' came your reply.  
'How'd you know?'  
'I er.. heard her say it whilst she was on the phone to someone.'  
He nodded in agreement.

You stayed like that a while before you asked 'What you wanna do whilst we wait?'  
'A-actually, I've got a-an erm.. Ide-ea, so er, take my hands and brace yourself, yea?' he stuttered. You complied, taking hold of his hands, already knowing he was going to teleport the both of you to some place. You closed your eyes, knowing from experience that if you kept them open you'd feel like you were gonna puke at the end of it.  
'We're here...' he whispered as you opened your eyes. You were on top of a hill, looking out at the small town below you ' _Wow... it's beautiful!_ ' you smiled before walking towards the bench and sitting down, staring down at the beautiful view.

You felt Sans sit down next to you as you looked up at him. 'Thank you for bringing me here, Sans'  
'Heh.. well, kid. This isn't the only reason I brought you here..' he picked your hand up, grabbing your attention completely as you stared up at him '..a-actually, I er. Shit um. I've liked ya for a while, um. I dunno how you feel about dating a guy, especially a guy monster, heh, kinda fucked up of me isn't it, I'm already ya best friend right? Am I ya best friend? Am I selfish for wanting more with you? Fuck um.. I'm rambling, sorry...'  a very deep blue blush tinted his cheeks as you stared at him, eyes wide, face burning. '..But um, it's cool if ya don't see me as anything more heh.. um.. er, (Y/n).. I'm sorry.. I- Ugh. Forget I said anything.' He dropped your hand as he got up 'L-lets go back to Tori's and forget this, yeah?'

You were absolutely lost, _Sans_.. your _crush_.. your _best friend_.. he liked you back?! Holy shit he liked you back and you sat there like a fucking moron?! What the- Oh. My. _Stars_.  
'Kid?' Sans asked, waving a hand in front of you, trying to get your attention back.  
You didn't have a fucking clue what to do, but it seems your heart took over in that moment...  
'I FUCKING LOVE YOU SANS!' you screamed at him, not really meaning to be so loud but honestly, you couldn't really care at that moment  
'Y-you, you love me?!' He looked so shocked as you nodded 'I-I love you too, (Y/n).'  
You pulled him down, smashing your lips against his teeth in a 'kiss'. 'F-fuck Sans...' you said quietly.

Within the blink of an eye you were in his room, you at the bottom, him on top, his eye shining blue flames as he held himself above you.  
'I-I've waited so fucking long to take you...' he leant down and licked at your neck, sucking it.. '..now I'm finally able to have you. All. To. Myself.'  
You whimpered as you felt the heat rushing throughout your body. 'S-Sans, wait a s-second, there.. there's something you gotta know..' you felt panic rush over you at the realization you had to tell him his before he found out himself.  
He stopped, listening to what you had to say. 'I.. I'm.. I was born a girl.' you closed your eyes, trying to stop the tears threatening to fall. He was gonna leave you and you've only just got him.. you just knew it. He wouldn't wanna be with you. 

He started down at you for a minute, sockets widening before he chuckled, which surprised you and you opened your eyes, to find his eye lights locked on you in the shape of hearts... _hearts_.. his eye lights were hearts, this was too fucking cute.  
'I love you for you, not for whats between your legs', he leaned down to kiss you gently. You felt so relieved at this, you wanted to cry tears of happiness.  
'To show you how much I love you...' he leaned closer to your ear, whispering 'I'm gonna make this the best birthday you've ever had..' he began to nip at your earlobe, making you shudder and grip at his shirt.

He began to remove your jumper, glancing back at you every now at then to make sure you were alright with it, once it was removed, he began licking up and down your chest, taking a nipple into his mouth whilst playing with the other between his phalanges, earning a gasp from you as you tried to remove his jacket and shirt, he either didn't know what you were trying to do or was purposely ignoring you as he began to make his way down to the bottom of your stomach, kissing along it with the odd bite. He began to undo your jeans, pulling them down along with your boxers to expose your naked pussy.  
You gasped as you felt his tongue run across your clit, gripping onto the bed sheets as he began to lick up and down your opening, tears of pleasure escaping your eyes as you tried your best to ignore the head building up in your lower abdomen. As he inserted a finger to your opening once he decided it was slick enough for it not to hurt you he looked back up at you.  
'This alright?'  
All you could do is nod at him as he began to wiggle his finger, earning a moan from you as he did so, the heat in your stomach tightening. 'G-goddamnit, Sans..' you whispered, gripping tighter as he inserted another finger scissoring them and searching for your sweet spot. You gasped as he grinned up at you.  
'Found it'

He began thrusting his two fingers it and out, abusing that spot and adding a third once he decided you were loose enough.  
'S-Sans I'm gon-' you couldn't finish your sentence as your vision was blurred as you came. You heard him chuckle looking up just as he removed the fingers from your entrance and licking off your fluids.  
'Heh, sweet, but not as sweet as you..' he purred, leaning in for another kiss.  
You blushed furiously as he finally began to take off his clothes, freeing his rather large blue, glowing dick, lowering it towards your loosened aperture.

You stared up at his skeletal frame, oh stars he was beautiful in every single way.  
'Sans.. I.. I want you.. Inside of me now, pleasee' you whispered, just loud enough for him to hear. You could feel your insides crying out to be filled by him, the one you loved.  
He gripped at your hips as he began to insert himself into you.  
'I love you so much..' he breathed '..I'll make you feel so good, I promise...' he begun working himself into you, stretching you wide as tears of pleasure escaped your eyes.  
'F-fuck.. so tight' he sighed as he became completely buried inside of your swollen pussy. 'Are you hurting?' he asked looking back towards your face.  
'No, oh stars, Sans, please..' you cried out '..move!'  
'Gladly' he growled as he pulled almost all the way out before pushing himself back into your warmth. He watches you intently for his first few thrusts before he becomes satisfied with the fact that you are definitely not in pain. You wrapped your legs around his pelvis as he continues to pick up his pace, he leans down onto your neck biting at the skin, making you bleed, before licking it.  
When you came, you came hard, screaming his name as you came down from your high.

When you were back to your senses, you realized Sans had still not finished and was still thrusting deep inside of you, getting faster each time he did so.  
_'Mine mine mine mine mine mine mine mine mine mine mine mine mine mine mine...'_  
He just repeated it over and over again, thrusting harder, faster, somehow, _deeper_ , into you that the one before, biting down on your neck, drawing out more blood which he licked up and sucked at. You clinged to him tighter as his pace got quicker and quicker to the point that it was slightly uncomfortable, but you held on, wanting him to cum too.. He made you feel good, you had to at least let him do this... right?

He thrust into you a few more times before you felt his magic spill into you as he grunted and bit down harder on your neck. He collapsed next to you as he pulled himself out of you, his magic spilling out as he did so. You cuddled closer to him as he brought his arms around you.  
' _Wow_ ' you heard him breathe. You chuckled at him as you cuddled closer, letting sleep take you.

A few hours later you heard a phone buzz and you groaned, Sans had you locked between his arms, still fast asleep.. _Great_. You tried to untangle himself to check on the time but his grip just tightened 'Saaaans, let me go' you whined. He groaned and opened his eye sockets, then closed them again.  
'5 more minutes...' his grip tightened even further.  
'Sans we gotta get back to my mother's... fuck SANS! They'll be wondering where we are!' you panicked trying harder to loosen his grip on you.  
'Heh, fine' he released you and stretched, a lazy smile gracing his features.  
You found your phone on the floor. How the fuck-? Y'know what, just be happy it didn't break? You checked your phone to see missed calls from Toriel, Papyrus, Undyne and Alphys, even a text message from Mettaton wondering where you were. One text sure caught your eye though.  
  
'Waddup punk! Stop fucking that skeleton and get to your party!' you blushed, clearly she was just teasing you but if she knew that's what had actually happened... you shook your head and slapped your cheeks.  
'C'mon then, get dressed and I'll 'port us back to Tori's' came Sans' still very tired sounding voice. You nodded as you slipped your clothes back on.

_What a great birthday (so far)_. You thought as you took the hand of your boyfriend, ready to teleport to your next birthday surprise.

 


End file.
